A lithium ion secondary cell includes positive and negative electrodes capable of reversibly occluding and releasing lithium ions, and an electrolyte interposed between both the electrodes. The lithium ions in the electrolyte come and go between both the electrodes for performing charging and discharging. The energy density is high. For this reason, use thereof has been also studied in the fields requiring a large-capacity power source such as hybrid vehicles and electric cars. Representative examples of the electrolyte for use in a lithium ion secondary cell may include a liquid electrolyte (non-aqueous electrolyte) containing a lithium salt as a supporting salt in a non-aqueous solvent. Representative examples of the supporting salt may include lithium slats including fluorine as a constituent element such as lithium tetrafluoroborate and lithium hexafluorophosphate. Patent Document 1 describes a technology regarding a lithium ion secondary cell using such lithium salts. As other technical documents regarding a lithium ion secondary cell, mention may be made of Patent Documents 2 to 5.    Patent Document 1: Japanese Patent Application Laid-open No. 2005-32716    Patent Document 2: Japanese Patent Application Laid-open No. 2004-111349    Patent Document 3: Japanese Patent Application Laid-open No. 2008-16414    Patent Document 4: Japanese Patent Application Laid-open No. 2008-84689    Patent Document 5: Japanese Patent Application Laid-open No. 2008-539548